The subject matter disclosed herein relates to a fuel heating system, and more particularly, to heating fuel during startup of a gas turbine engine.
A gas turbine engine combusts a mixture of fuel and air to generate hot combustion gases, which drive rotation of one or more stage of turbine blades. In turn, the rotation may be used to drive a load, such as an electrical generator. During startup, it is desirable to rapidly bring the gas turbine engine to a load level where its exhaust emissions are in compliance with the pertinent regulations. The faster the gas turbine reaches this so-called “emissions-compliant” load level, the smaller is the total amount of harmful emissions. The rate of loading is dependent on the stable operation of the combustor of the gas turbine, which is primarily controlled by the fuel temperature. In modern gas turbines, during normal base load operation gaseous fuel is heated to improve the thermal efficiency. This heating is typically accomplished by the hot feed water extracted from the heat recovery steam generator (HRSG). Unfortunately, during a plant startup after a sufficiently long down time, the HRSG is not able to provide the hot water needed for gaseous fuel heating to a level required by stable combustor operation.